diff --git a/ext/standard/php_string.h b/ext/standard/php_string.h
index 03d1ee8f8ce..53209f44851 100644
--- a/ext/standard/php_string.h
+++ b/ext/standard/php_string.h
@@ -143,11 +143,6 @@ PHPAPI int string_natural_compare_function_ex(zval *result, zval *op1, zval *op2
 PHPAPI int string_natural_compare_function(zval *result, zval *op1, zval *op2);
 PHPAPI int string_natural_case_compare_function(zval *result, zval *op1, zval *op2);
 
-#ifndef HAVE_STRERROR
-PHPAPI char *php_strerror(int errnum);
-#define strerror php_strerror
-#endif
-
 #ifndef HAVE_MBLEN
 # define php_mblen(ptr, len) 1
 # define php_mb_reset()
diff --git a/ext/standard/string.c b/ext/standard/string.c
index 3b8f306be43..c78ec5ffacd 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -3732,24 +3732,6 @@ PHP_FUNCTION(stripslashes)
 }
 /* }}} */
 
-#ifndef HAVE_STRERROR
-/* {{{ php_strerror
- */
-char *php_strerror(int errnum)
-{
-	extern int sys_nerr;
-	extern char *sys_errlist[];
-
-	if ((unsigned int) errnum < sys_nerr) {
-		return(sys_errlist[errnum]);
-	}
-
-	(void) snprintf(BG(str_ebuf), sizeof(php_basic_globals.str_ebuf), "Unknown error: %d", errnum);
-	return(BG(str_ebuf));
-}
-/* }}} */
-#endif
-
 /* {{{ php_stripcslashes
  */
 PHPAPI void php_stripcslashes(zend_string *str)
diff --git a/main/php.h b/main/php.h
index 888344324ee..48b4633879c 100644
--- a/main/php.h
+++ b/main/php.h
@@ -230,10 +230,6 @@ typedef unsigned int socklen_t;
 #include "zend_stack.h"
 #include <string.h>
 
-#ifndef HAVE_STRERROR
-char *strerror(int);
-#endif
-
 #if HAVE_PWD_H
 # ifdef PHP_WIN32
 #include "win32/param.h"